glucosúria

Glucosuria, or glycosuria, is the presence of glucose in the urine. It occurs when the amount of glucose filtered by the kidneys exceeds the proximal tubule's capacity to reabsorb it, or when the renal reabsorptive mechanisms are impaired. The renal threshold for glucose is typically around 180 mg/dL; when blood glucose rises above this level, glucose appears in the urine. Glucosuria can also result from disturbances in proximal tubule function, independent of blood glucose levels.

Common causes include physiological or transient glucosuria after a high-carbohydrate meal in healthy individuals, and pathological glucosuria due to elevated blood glucose as seen in diabetes mellitus (type 1 or type 2). Pregnant women may also show glucosuria due to increased glomerular filtration and altered renal handling of glucose. Less common causes involve renal glycosuria from defects in glucose transporters (such as SGLT2 or SGLT1) or proximal tubule disorders like Fanconi syndrome, as well as certain medications that promote urinary glucose loss, including SGLT2 inhibitors used in diabetes management.

Diagnosis typically begins with a urine test, such as a dipstick or laboratory urinalysis, which detects glucose in the urine. Because glucosuria can occur with otherwise normal blood glucose, it is important to measure blood glucose or HbA1c to assess glycemic status and to investigate potential renal causes if hyperglycemia is not present.

Management focuses on the underlying cause. In diabetes, improving glycemic control is central. In pregnancy, monitoring and management according to obstetric guidelines are essential. When glucosuria persists with normal blood glucose, evaluation for renal glycosuria or tubulopathies may be indicated.